Bone structures or bone parts in the human body may be destroyed due to inflammatory processes, malignant tumors or traumatic events; they may be replaced by suitable prostheses. Apart from metals, which are used to replace highly strained bone structures, ceramic prostheses serve for replacing less strained bone structures, such as in the region of the head. Ceramic materials are used in this region for reconstructing, e.g., parts of the auditory ossicle chain, of the auditory walls or even of the jaw.
Prosthetic parts must be adapted to the given individual dimensions and conditions. This is difficult to be done with ceramic prostheses due to their complicated workability. Consequently, dimensional adjustability is a chief requirement in the design of ceramic protheses, whereas given natural anatomic conditions can take into account only to a minor extent. A single-piece middle ear prosthesis designed according to this concept is described, e.g., in German Patent Specification 2,905,183.
Heterologous bone grafts, which are equally employed, are not always available and have proven to be problematic in view of possible HIV infections.